Hi there ~
I understand your concern. It would benefit for you to have good foreplay and afterplay, and not just intercourse. If you need further information you might benefit from seeing a sexologist
or reading up more on foreplay. Women like foreplay and rarely do they say that sex is not satisfying. It might help to take your wife with you to a sexologist for therapy or to a psychotherapist for counseling regarding intercourse and also courting, to build the relationship.
Also regarding the red spots it is best to use what your doctor suggested. It may also be helpful to have a surgical opinion as to why you are not able to pull your foreskin back as it might be phimosis
. I believe that it is easily treated with circumcision
. I also hope that you get a second opinion
regarding your dermatological medications and STD
testing done to be able to determine the cause of your rashes. Keeping good sexual / genital hygiene is also helpful.
Take care and have a lovely day!